Red soils are characterised by acidic pH and limitations in carbon, nitrogen, water, and soil structure. To overcome such limitations, improved soil aggregation is the key to improving the physical and chemical properties of soil. Applying organic amendments such as straw can lead to corresponding soil aggregation and stability changes. Therefore, we explored the short-term effects of rice straw amendment, either alone or in combination with biochar, on improving the carbon fractions, stability, and composition of soil aggregates in red soil with a history of vegetable planting. The study consisted of four treatments: control (no organic material, CK), biochar alone (5% homemade straw biochar, B), straw alone (12% rice straw, S), and biochar with straw (5% homemade straw biochar + 12% rice straw, BS). Our results showed that equal amounts of straw and biochar substantially reduced the number of mechanically stable aggregates (MSA), mean weight diameter (MWD), and geometric mean diameter (GMD) of the soil. BS treatment reduced >0.25 mm aggregate content (R0.25), MWD and GMD by 24.06%, 56.81%, and 62.19%, respectively, compared with that of the control. The addition of straw greatly enhanced the water-stable macromolecular content and stability coefficient of the soil, but treatment B had no obvious effect. The S treatment had the greatest effect on R0.25, MWD and GMD, increasing them by 143.94%, 246.67%, and 181.82%, respectively, compared with that of the control. Soil organic carbon (SOC) was significantly increased by straw addition and carbonisation treatment, and the effect of the BS treatment was the best, with an increase of 325.63% compared with that of the control. The organic carbon content in the aggregates of different particle sizes treated with different organic materials also increased significantly. In the soil reactive organic carbon fraction, applying biochar alone did not affect microbial biomass carbon (MBC), dissolved organic carbon (DOC), or easily oxidized organic carbon (EOC) but could increase the particulate organic carbon (POC) content. All the treatments with straw application significantly increased the MBC, DOC, EOC, and POC content, and the highest effect was obtained by applying both straw and biochar in an integrated form, i.e., the BS treatment. In conclusion, the co-application of biochar and straw sequestered more carbon and revamped soil C pools than either biochar or straw alone and could be a promising option for the sustainable use of red soils to ameliorate the aforementioned limitations associated with this soil type.

Mixed salt stress significantly inhibits pepper germination and seedling growth, but it is unclear whether the negative effect can be mitigated by selenium (Se) addition. Four pepper varieties with large differences in salt tolerance were used as materials in this study. Based on the significant stress of mixed salts, the concentration of sodium selenite was set to 0, 5, 10, 20, 40, 80, and 120 µmol L− 1, respectively. Various parameters related to seed germination, seedling growth and development, as well as internal physiological indicators were measured, and the alleviating effects of sodium selenite on salt stress was comprehensively evaluated by fuzzy membership function method. The results showed that with the increase of sodium selenite concentration, the germination rate, relative salt damage mitigation rate, root fresh weight, fresh weight above ground, root length, hypocotyl length, and seedling activity index all showed an initial increase followed by a decrease, while the contents of superoxide anion radical (O2−), malondialdehyde (MDA), proline (Pro) and the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) decreased first and then increased. On the whole, the total weighted values of membership function values of each index of the four varieties increased first and then decreased with the increase of sodium selenite concentration. The addition of appropriate concentration of exogenous sodium selenite (10–20 µmol L− 1) significantly improved seed germination of pepper, meanwhile, it alleviated the effect of salt stress and promoted root and above ground growth by significantly reducing the content of O2− and MDA. The appropriate concentration of exogenous Se could promote the growth and development of pepper seedlings and ensure the cultivation of strong seedlings by promoting the early and rapid germination of seeds and reducing the degree of stress.

[目的]研究喷施赤霉素缓解多效唑对叶用莴苣幼苗抑制作用.[方法]采用叶用莴苣不同品种与不同质量浓度的赤霉素进行双因素完全随机试验设计,采用5 个叶用莴苣品种,赤霉素质量浓度以有效成分计,分别设A1(0 mg/L)、A2(15 mg/L)、A3(30 mg/L)、A4(60 mg/L)、A5(120 mg/L)、A6(240 mg/L)和A7(480 mg/L)共7 种喷施水平,于叶用莴苣移栽期测定幼苗素质、叶形及叶片可溶性固形物含量.[结果]随赤霉素质量浓度增加,各叶用莴苣品种的株高、根鲜重、根干重、地上部鲜重、地上部干重、总叶面积、总叶长、总叶宽、最大功能叶叶长及最大功能叶叶宽均先增后降,各指标值均在A5 处理时达最大,与A1 处理相比,A5 处理各指标分别增加 36.8%～86.6%、30.1%～53.4%、21.1%～77.7%、56.2%～127.3%、56.0%～115.5%、63.4%～142.1%、30.4%～79.5%、27.0%～65.7%、24.0%～50.0%及 21.8%～48.8%.可溶性固形物也呈现先增后降的趋势,以A2 处理、A3 处理表现最佳.叶用莴苣各品种SPAD值及根冠比先降后增,各指标值均为A5 处理最低,与A1 处理相比,A5 处理各指标分别降低 17.6%～28.6%及 17.5%～36.2%.[结论]喷施赤霉素具有缓解多效唑抑制的作用,其中赤霉素质量浓度在A5(120 mg/L)时对叶用莴苣幼苗的调控效果最佳.

[目的]近年来中国设施蔬菜产业高质量迅速发展,有效实现蔬菜周年均衡供应、菜农增收致富并提高蔬菜质量安全水平.江西省赣州市顺势而为,设施钢架大棚面积从2015年的0.07万hm2到2021年建成总面积1.90万hm2,如何高质量发展赣南设施蔬菜产业是打造成蔬菜富民产业的关键措施,其中保障蔬菜质量安全至关重要.土壤重金属含量超标直接影响农产品质量安全及作物生长,通过对设施土壤重金属分布特征、生态危害程度及来源开展解析,深入分析设施土壤质量安全问题,实现设施土壤安全预警、有效修复及科学利用.[方法]2021年,以江西省赣州市设施蔬菜基地为研究对象,结合赣南设施连片蔬菜大棚的分布及其面积,根据代表性、典型性、均衡性的采样布点原则,采用GPS定位系统布设并采集235件0～20 cm耕层土壤样本,测定土壤采样点的经纬度、海拔、土壤重金属(Cu、Zn、As、Cd、Pb)含量及土壤理化性质.[结果]研究区土壤Cd、Cu、As、Pb、Zn平均含量分别是江西省土壤背景值的5.30、1.48、1.34、1.03、0.97倍;通过单因子污染指数法分析,土壤Cd、Cu、As、Pb受污染的样点数分别占总样点数的55.7％、6.4％、3.4％、1.7％.设施土壤重金属综合污染指数(PN)及综合潜在生态危害指数(RI)平均值分别为1.4(0.5～14.8)及62.0(23.6～651.7),PN属轻度污染水平,RI为轻微程度,其中Cd是最为主要的生态风险因子;PN及RI的中位数分别为0.9及40.5,均较小于平均值且变异系数较大,说明土壤重金属较大区域处清洁水平或污染较轻,局部区域污染较严重.赣南设施土壤重金属Zn、Pb积累以自然源为主,Cd、As、Cu主要与人为因素有关,其高含量地区均与钨矿区相对应,特别是Cd与钨矿共(伴)生关系最为密切相关.[结论]赣南设施土壤整体生态风险较低,其中Cd是最关键的风险贡献因子,应当予以充分重视,建议在酸性红壤区对生物移除土壤Cd及其安全利用深入研究,并持续监测其动态变化.

细胞分裂素具有促进植物细胞分裂等作用,能否通过喷施细胞分裂素来提高生菜穴盘育苗质量目前尚不明确.设品种与细胞分裂素浓度双因素完全随机试验,生菜供试品种分别为玻璃生菜、耐抽苔生菜、罗马直立生菜、香港软尾生菜、奶油生菜,细胞分裂素浓度(以产品重量计)分别设A1(0g/L)、A2(0.35 g/L)、A3(0.7 g/L)、A4(1.4 g/L)和A5(2.8g/L)共5种喷施水平.2020年探讨了穴盘基质育苗下苗期不同浓度细胞分裂素对南方生菜幼苗素质、叶型及地上部可溶性固形物含量的影响.随细胞分裂素浓度增加,各品种幼苗根冠比均呈先降后增趋势.而各品种幼苗株高、SPAD值、单株根鲜重、根干重、地上部鲜重、地上部干重、单株总叶面积、单株总叶长、单株总叶宽、最大功能叶叶长、最大功能叶叶宽及地上部可溶性固形物含量却均呈先增后降.其中耐抽苔生菜和香港软尾生菜的上述指标均在喷施1.4 g/L细胞分裂素(A4)时最高,而其他品种在喷施0.7 g/L细胞分裂素(A3)时表现最佳.苗期喷施适宜浓度细胞分裂素可显著提高生菜幼苗素质、叶型参数及地上部可溶性固形物,其中耐抽苔生菜和香港软尾生菜以A4(1.4 g/L)时生长发育表现最好,而奶油生菜、罗马直立生菜及玻璃生菜却在A3(0.7 g/L)时生长发育达到最佳.

To determine the salt tolerance and physiological mechanism of pepper (Capsicum annuum L.) at the germination stage, the Hongtianhu 101 and Xinxiang 8 varieties, which have large differences in salt tolerance, are employed as the study materials. Six mixed salt concentrations of 0, 3, 5, 10, 15, and 20 g/L derived using equal molar ratios of Na2CO3, NaHCO3, NaCl, CaCl2, MgCl2, MgSO4, and Na2SO4 are used. To determine their effects, the related indexes of seed germination, seedling growth, and physiology are measured, and salt tolerance is comprehensively evaluated using membership function analysis. The results show that as the mixed salt concentration increases, the germination potential, germination index, germination rate, seed germination vigor index, root length, and root fresh weight of the two cultivars significantly decrease, whereas the relative salt rate gradually increases. The hypocotyl length and fresh weight aboveground increase first and then decrease, while the malondialdehyde (MDA), proline (Pro) content, catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activity decrease and then increase. The germination potential, germination index, germination rate, seed germination vigor index, root length, root fresh weight, MDA and Pro content, and CAT activity of the Hongtianhu 101 seeds are higher than those of Xinxiang 8 for all salt concentrations employed here. However, hypocotyl length, fresh weight aboveground, and relative salt rate are lower in Hongtianhu 101 than in Xinxiang 8. The comprehensive evaluation of salt tolerance reveals that the total weighted values of the two membership function indexes increase first and then decrease as the mixed salt concentration increases. Compared with 5 g/L, which has the highest membership function value, the index under salt concentrations of 3 g/L, 10 g/L, and 15 g/L decreases by 4.7%-11.1%, 25.3%-28.3%, and 41.4%-45.1%, respectively. This study provides theoretical guidance for the breeding of salt-tolerant varieties of pepper and an analysis of the physiological mechanisms involved in salt tolerance and salt-tolerant cultivation.

【Objective】The study was carried out to explore the effects of different concentrations of uniconazole in plug media on the growth and development of different varieties of lettuce seedlings.【Method】Five lettuce varieties in southern China were used to study the effects of different concentrations (0-50 mg/L) of uniconazole on seedling growth, leaf shape parameters and soluble solids (TSS) of lettuce.【Result】With the increase of uniconazole concentration, the root fresh weight, root dry weight, shoot fresh weight and shoot dry weight of seedlings of various lettuce varieties increased first and then decreased. The root fresh weight and dry weight of bolting-tolerant lettuce and Roman upright lettuce were the highest under 10 mg/L uniconazole treatment, and those of other varieties were the highest under 5 mg/L uniconazole treatment. The total leaf width, maximum functional leaf width and total leaf area of seedlings also reached the maximum under 5 mg/L uniconazole treatment. The total leaf width and total leaf area of butter lettuce seedlings were larger than those of other varieties. The root-shoot ratio of iceberg lettuce, butter lettuce and bolting-tolerant lettuce increased with the increase of uniconazole concentration, while the root-shoot ratio of Hong Kong soft-tail lettuce and Roman upright lettuce increased first and then decreased. In addition, under the treatment of 50 mg/L uniconazole, SPAD values of lettuce seedlings of all varieties increased significantly, while plant height, total leaf area and TSS accumulation were severely inhibited.【Conclusion】Strong seedlings of lettuce could be cultivated by the medium with suitable concentration (5 mg/L) of uniconazole. The growth and development of lettuce seedlings would be inhibited by higher concentration of uniconazole.

为探究江西省赣州设施菜地土壤全硒(Se)的含量及其分布特征,于2021年对赣南地区设施蔬菜大棚采集0～20 cm耕层土壤样235件,测定了土壤采样点的经纬度、海拔及土壤中全硒含量和理化性质.结果表明,赣南地区设施菜地土壤全硒质量分数平均为0.31 mg/kg,变化范围为0.03～1.25 mg/kg,全硒含量分布频率符合正态分布.研究区域设施菜地富硒土壤资源较为丰富,85.1％的样点数土壤全硒含量处于足硒及以上水平(>0.175 mg/kg),其中有22.1％的样点数土壤属于富硒水平标准(>0.400～3.000 mg/kg),而富硒土壤主要集中在赣南地区的正西部及东北部等部分区域;7.2％和7.7％的样点数土壤全硒质量分数分别达硒不足(>0.125～0.175 mg/kg)和潜在硒不足水平(≤0.125 mg/kg),二者主要集中在赣南地区西南角部分区域,不存在硒中毒区域.海拔每增加1 m,设施土壤全硒质量分数降低5.35×10-4 mg/kg;纬度每增加1°和pH值每增加一个单位,土壤全硒质量分数分别增加0.090和0.049 mg/kg.综上,赣南地区设施菜地土壤硒资源具有较大利用潜力,并可依据研究区域全硒含量分布特征开展具有针对性的设施富硒蔬菜发展策略.

以5种生菜为试材,使用穴盘基质拌施多效唑育苗来模拟土壤多效唑残留的方法,其中多效唑浓度(以有效成分计)设置A1(0 mg·L-1)、A2(2.5 mg·L-1)、A3(5.0 mg·L-1)、A4(10.0 mg·L-1)、A5(20.0 mg·L-1)、A6(40.0 mg·L-1)和A7(80.0mg·L-1)共7种残留水平,研究了多效唑残留对生菜幼苗质量、叶型及地上部可溶性固形物含量的影响,以期探明生菜育苗生长对多效唑残留浓度的响应机制.结果表明:随多效唑浓度增加,各生菜株高、地上部鲜质量、地上部干质量、总叶面积、总叶长、总叶宽、最大功能叶叶长、最大功能叶叶宽及可溶性固形物均降低,SPAD值及根冠比均增加,而根鲜质量及根干质量先增后降.其中A5、A6和A7处理株高、地上部鲜质量、地上部干质量、总叶面积及可溶性固形物等指标均显著低于A1处理,SPAD值和根冠比等指标却均显著高于A1处理.随菜地多效唑残留浓度增加,各生菜苗期生长发育受抑制程度增加,其中多效唑残留浓度为A5(20 mg·L-1)及其以上时其抑制效果均达显著水平,对生菜育苗质量极为不利.

[目的]增施氮肥是实现水稻高产最为重要的措施之一,但过量施用氮肥会降低氮肥吸收利用率并造成氮素面源污染.合理的每穴苗数通过调节稻田基本苗数构建高产群体起点,但通过增加每穴苗数降低施氮量能否同步实现水稻高产及氮素高效利用目前还不清楚.旨在探索每穴苗数及氮肥用量对构建晚籼稻高产氮高效群体的协同调控效果.[方法]于2017—2018年,选用五优308及天优华占为晚籼稻材料,设CK(每穴2苗和N 180 kg/hm2)、T1(每穴3苗和N 144 kg/hm2)及T2(每穴4苗和N 126 kg/hm2)等3个处理,测定了水稻干物质生产、叶面积指数、产量及氮素吸收利用.[结果]随着增苗减氮调控程度增加,两品种产量均先增后降.与CK处理相比,五优308及天优华占品种T1处理产量分别增加0.36％～0.38％及8.73％～10.01％,其中天优华占T1处理与CK处理产量间差异达显著水平;天优华占T2处理产量增加0.95％～1.72％,而五优308品种T2处理产量却显著降低7.46％～7.96％.增苗减氮促进晚籼稻有效穗数增加,每穗粒数降低,结实率先增后降,千粒质量无显著变化.两品种抽穗期及成熟期的叶面积指数及幼穗分化期至成熟期的光合势均先增后降,五优308作物生长速率、总干物质量降低,而天优华占作物生长速率、总干物质量却均先增后降.总吸氮量降低,氮素偏生产力增加、氮素吸收利用率、生理利用率及农学利用率均先增后降.[结论]T1处理可同步协调"增苗"与"减氮"二者关系,可有效构建晚籼稻高产氮高效群体,但具体调控效果因品种而异.